Nowadays almost every desktop computer, laptop, tablet, and smartphone is connected to the Internet and the emergence of the Internet and Things (loT) will provide global Internet connectivity to a broader variety of devices. Wi-Fi, which is based on the Institute of Electrical and Electronics Engineers' (IEEE) 802.11 standard, dominates the consumer electronics market and any loT device that needs to connect to smartphones, tablets, televisions, set-top boxes, game consoles, and toys would benefit from Wi-Fi connectivity. Unfortunately, the energy consumption of Wi-Fi is relatively high and can quickly drain the battery of any battery-powered device using a Wi-Fi connection.
To alleviate the problem of power consumption, the IEEE 802.11 standard specifies a Power Saving Mode (PSM) that allows an idle 802.11 device to transition from an awake state to a low-power doze state by switching off the radio transceiver. However, standard PSM is only designed for single-hop communications. As such, when a data packet needs to be forwarded over multiple hops, standard PSM may significantly increase the delivery delay, because only the next-hop device is notified about the pending data packet via traffic announcement. Therefore, devices on subsequent hops will remain in a doze state until the next beacon interval. This causes the data packet to be delayed for multiple beacon intervals before it arrives at the destination device.